CZ252894A3 - Pyrotechnic ignition mixture for technically demanding systems and extreme conditions - Google Patents

Abstract

The invention concerns a pyrotechnic ignition mix for technically demanding initiation systems and extreme conditions. It can be used for civil pyrotechnic systems in automobile safety systems, such as airbags and belt tighteners, like squibs containing ignition mixes based on sodium salts of picramine acid, potassium perchlorate, stibnite sulphide and VITON fluoroelastomer, which is a copolymer of vinylidene chloride, hexafluorpropylene and tetrafluorethylene in a mass ratio of individual components of:Sodium saltpicramine acid: 10 - 40 parts,potassium perchlorate: 30 - 60 parts,stibnite sulphide: 10 - 30 parts,VITON B: 1 - 8 parts.This ignition mix with particle size from 0.1 to 0.5 mm, placed in the squib, ensures reliable ignition of the airbag gas generator or workload of the belt tightener even under extreme conditions, such as a temperature of -35 degrees C to +85 degrees C, high relative humidity, high vibration, featuring high chemical stability, tested heat exposure to 125 degrees C for 400 hours, and ensures thermal self-ignition of the pyrosystem at increased temperatures of 245 to 255 degrees C.

Description

Pyrotechnic ignition composition for technically demanding initiation systems and extreme conditions

Technical field

FIELD OF THE INVENTION The present invention relates to a pyrotechnic ignition composition for military specialty and civil pyrotechnic systems in the field of automobile airbag and car seatbelt safety systems. These systems are activated by the use of explosive compositions, which are sensitive to initial forms of stimulus such as mechanical stimuli (friction, stab, impact), electrical stimuli (electric spark) and thermal stimuli (elevated temperature, flame). The explosive composition does not meet all the requirements for ignition of the main pyrotechnic charge of the system and does not ensure its required function even under extreme conditions of use, and therefore the desired function is achieved by using ignition compositions which with their advantageous properties transfer ignition to the pyrotechnic charge.

These ignition components must function reliably in environments of extreme temperatures, high relative humidity and extreme vibration, with the requirement of high chemical stability, faultless function and reliability for at least 15 years. The ignition composition is also required to be able to heat self-ignite at elevated temperature, which prevents the explosion of the pyrotechnic charge exposed to elevated temperature.

BACKGROUND OF THE INVENTION

Reliable and perfect performance of military specialty systems and civilian pyrotechnics in the area of car safety systems for airbags and car seat belt tensioners is decisively influenced by the design and technology of the ignition composition, which transmits, directs and amplifies the lack of ignition. its required function even under extreme conditions of use. The explosive wraps around the resistive wire, which, after passing the current generated by the piezocensor, gets warmer when the car crashes and ignites it with the released heat.

A desirable property of the ignition composition is sensitivity to reaction products

- 2 explosive styles, a well-defined rate of chemical reaction, the rate and amount of heat generation with a defined content of solids and gases in the combustion products that determine its ignition capability. These properties must be maintained even under extreme effects of temperature, humidity and vibration even after exposure to elevated temperature, which simulates the natural aging of the composition and is a measure of its chemical stability.

To achieve these properties, black-powdered firearms containing potassium nitrate, sulfur, charcoal, smokeless gun powders containing nitrocellulose and nitroglycerine and pyrotechnic mixtures are used, where the nitrate, perchlorate or potassium chlorate with combustibles such as zirconium, titanium, boron and binders such as nitrocellulose, resin or sulfur. However, these compositions do not simultaneously meet all the required properties, in particular the requirement of high chemical stability, the self-ignition properties at elevated temperature and the resistance to high humidity, vibration and extreme temperatures.

SUMMARY OF THE INVENTION

Ignition composition with self-ignition capability in the temperature range from 245 ° C to 255 ° C, with high chanic stability verified by thermal exposure at 125 ° C for 400 hours, which simulates natural aging of the composition and with the ability to reliably ignite the main pyrotechnic charge of military systems special techniques and civilian pyrotechnics in the field of car safety systems for airbags and belt tensioners in extreme conditions, such as high relative humidity, temperature from -35 'to + 85'C, high vibration, is achieved by solution of pyrotechnic ignition composition for technically demanding initiation systems and extreme, conditions of use based on the sodium salt of picramic acid, potassium perchlorate, antimony simic, and VITCNU fluoroelastomer.

• The ignition component containing these components technologically prepared by the method of granulation from a solution of VITON in a volatile solvent followed by compression ¹ and crushing of tablets ensures high sensitivity to thermal expression of the explosive composition and optimal energy content in reaction products of high heat capacity ensures all required properties the ability to ignite the pyrotechnic charge of these systems, even under extreme conditions of use.

Examples of embodiments of the invention

The pyrotechnic ignition composition for technically demanding initiation systems and extreme conditions of use is a mixture of the sodium salt of picramic acid, potassium perchlorate, the antimony trioxide and the fluoroelastoner VITON B in the following percentage composition:

Picaminic acid sodium salt: 19% Potassium perchlorate: 58% Antimony sulphide: 19% VITON B: 4%

Said ignition composition technologically prepared by granulation method from a solution of VITCNU B dissolved in acetone and after drying compacted by compression into tablets.

I and crushed into grains having a size of 0.2 to 0.8 mm, it is worked out into a known structure of sguibus, which is activated by a current pulse applied to a resistive wire encased in an explosive composition. The explosive composition is initiated by the released heat and transmits the thermal stimulus to the ignition composition, which ensures the ignition of the airbag gas generator or the ignition of the working pyro compound of the car seat belt tensioners even under extreme conditions of car motor operation such as vibration, relative humidity. to + 85 ° C.

Example of the measured pressure values of the reaction gases of the given ignition composition stressed at 125 ° C for 400 hours and sinusoidal vibrations of parameters (3.5g, 8 hours, 6 - 2000 Hz) in a 2 cm ³ test bomb versus time from The beginning of the current pulse applied to the resistance wire of the squib at extreme temperatures is given in Table 1. i

The ignition composition has a flame retardant property at a temperature of from 245 ° C to 255'C, which is verified by increasing the temperature of the composition with a thermal gradient of 5 ° C per minute.

Table 1:

Pressure at -35‘C γ

pmax pyns t ₂ bar ₌₌₌ S ± ₌₌₌₌ tpmax diameter 8.37 6.70 1.50 1.73 2.75 max. 9.1 7.95 1.65 1.92 3.03 min. 7.8 6.12 1.38 1.59 1.80 st.odch. 0.37 0.30 0.08 0.10 0.37

- 4 Table 2:

Pressure curve at +85 ⁸ C

pmax p ^ ms t ₂ bar t 50 tpmax diameter 9.64 8.34 1,28 1.42 2.93 max. 10.1 9.00 1.38 1.50 3.57 min. 9.0 7.50 1.20 1.32 2.40 st.odch. 0.33 0.52 0.05 0.05 0.34

Symbols used:

pmax: maximum pressure of reaction products pyns: pressure at 7 ms t ^ bar: pressure at 2 bar t _r bar: pressure at 50 bar tpmax: time at maximum pressure

Industrial Applicability:

Pyrotechnic ignition component for technically demanding Civilian fireworks initiation systems in the field of automotive safety systems. Advantageously, its reliable ignition properties can be utilized in the squib design, designed to ignite an airbag inflator or to ignite a working pyro-compound of belt tensioners in harsh environments such as -35 ° C to 85 ° C, maximum relative humidity, vibration, its high chemical stability, verified by an artificial aging test at 125 ° C for 400 hours, and thermal self-ignition at 245 ° C to 255 ° C, which prevents the gas generator from exploding airbag or belt tensioner.

QU 7SU- Pfr

Claims (3)

PATENT E CLAIMS 1. Pyrotechnic ignition composition for technically demanding initiation systems and extreme conditions in automotive safety systems such as sguiby 'airbags and belt tensioners, characterized by high chemical stability under thermal stress of 125'C for min. 400 hours, has a self-ignition capability at temperatures from 245'C to 255'C and meets the conditions of use at operating temperatures from -35'C to + 85'C at relative humidity of up to 100% and high vibration. Pyrotechnic ignition composition according to claim 1, characterized in that it is determined by the composition of the following components and their percentage by weight, i.e., sodium picramine 10 -r 40%, potassium chlorate 30-60%, antimony sulfide 10-30% and VITON B 1-8%. 3. Pyrotechnic ignition composition according to claim 2, characterized in that it is produced, in particular, by granulation in a solution of fluoroelastomer in a volatile solvent, or by dry method by means of compaction and crushing, or both. 3. The pyrotechnic ignition composition according to claim 3, wherein the pyrotechnic ignition composition is formed in particular in the form of grains having a cylindrical shape having a diameter of 3 to 10 nm and a height of from 1 to 5.